Robotic surgical system with joint motion controller adapted to reduce instrument tip vibrations

In a controller for controlling movement of a robotic arm assembly in response to user manipulation of a master manipulator, a control system for controlling rotation of a slave joint of the robotic arm assembly, the control system comprising:

• a filter in a forward control path defined as being from the master manipulator to a motor coupled to the slave joint, wherein the filter attenuates frequency content of a joint position command generated from user manipulation of the master manipulator so that vibrations experienced at a tip of a surgical instrument held by the robotic arm assembly are reduced;
• and
• an inverse filter in a feedback path defined as being from a slave joint sensor to the master manipulator, wherein the slave joint sensor senses movement of the slave joint and the inverse filter provides a phase lead in the feedback path so as to at least partially compensate for a phase lag caused by the filter.

A method for reducing vibrations on a tip of a surgical instrument held by a robotic arm assembly without degrading stability of a control system controlling movement of a slave joint of the robotic arm assembly, the method comprising:

• attenuating a first signal indicating slave joint position commands generated from user manipulation of a master manipulator at frequencies beyond a cut-off frequency so that vibrations on the tip of the surgical instrument held by the robotic arm assembly are reduced at those frequencies;
• and
• amplifying a second signal indicating a position of the slave joint at frequencies above the cut-off frequency while providing phase lead to the second signal so as to at least partially compensate for delay caused by the attenuation of the first signal and stably generate a feedback signal provided to the master manipulation.